1. Field of the Invention
The present invention relates to a heat-curable binder based on an aqueous polymer dispersion comprising                an emulsion polymer (EP),        a polymer composed of at least 5% by weight of an ethylenically unsaturated monocarboxylic acid, dicarboxylic acid or dicarboxylic anhydride (acid polymer SP for short), and        monofunctional or polyfunctional epoxide compounds as curatives.        
The present invention further relates to a process for preparing the heat-curable binders based on an aqueous polymer dispersion and to their use as binders for moldings or nonwovens formed from fibrous or particulate materials.
2. Description of the Background
Heat-curable binders formed from polycarboxylic acids and polyols and/or alkanolamines are known, for example, from EP-A 445578, EP-A 583086, EP-A 882074, EP-A 882093 or DE-A 19949592.
EP-A 882074 and DE-A 19949592 specify, inter alia, alkoxysilanes as possible additives and curatives for such binders. As further additives and curatives for binders formed from polycarboxylic acids and polyols, EP-A 445578 discloses, inter alia, polyfunctional amines.
EP-A 576 128 describes adhesive compositions which comprise an acid-rich polymer component and a low-acid polymer component. The acid-rich polymer component is based on a monomeric mixture of from 40 to 95% of an alkyl acrylate or methacrylate and from 5 to 60% of an ethylenically unsaturated acid, such as acrylic acid or methacrylic acid. The low-acid polymer component is based on a monomer mixture of from 90 to 100% of an alkyl acrylate or alkyl methacrylate and from 0 to 10% of an ethylenically unsaturated acid. The composition is prepared by aqueous emulsion polymerization, the acid-rich polymer component being polymerized in the presence of the low-acid polymer component or vice versa. The pH of the composition is adjusted to the desired level by adding ammonium hydroxide or sodium hydroxide. The composition can be used as a pressure sensitive adhesive, laminating adhesive, adhesive for textiles, nonwovens, and packaging, and as wood glue.